Doping the Superatom with p-Elements: The Role of p-Block Endohedral Atoms in Bonding and Optical Properties of E@Au24(SR)18 (E = Si, Ge, Sn, and Pb) from Relativistic DFT Calculations

Expanding the versatility of well-defined clusters seeking distinctive physical and chemical behavior in a rational manner is a relevant issue in the design of functional nanostructures. Superatomic clusters through the prominent Au-25(SR)(18) aggregate offer an ideal template and robust framework to gain understading of the different behavior gained by the inclusion of different endohedral dopant atoms. Our results allow to gain more insights into the role of group XIV elements for both optical and bonding, revealing characteristic patterns to be expected in their low-energy UV-spectrum. The bonding shows an extension of the regular s-type interaction observed in [Au@Au-24(SR)(18)](-) to a more extended and covalent interaction given by s- and p-type interaction when the central atom is replaced by a group XIV elements, which can be expected of other endohedral p-block elements. In addition, the role of the spin-orbit coupling into the electronic and optical properties is discussed in terms of the new selection rules required by such regime. The characteristic optical and bonding patterns resulting from the p-element endohedral doping of the Au-25(SR)(18) superatom shed light into the rational variation of the molecular properties upon inclusion of an endohedral p-block element.